This invention relates to a method for producing a functional film. More specifically, this invention relates to a method for producing a functional film having an organic film comprising a particular polymer and an inorganic film.
Various functional films (functional sheets) including gas barrier films, protective films, and optical films such as optical filters and antireflection films are used in various devices including optical devices, display devices such as liquid crystal displays and organic EL displays, semiconductor devices, and thin film solar batteries.
The functional films have been formed by film formation (thin film formation) through vacuum deposition techniques such as sputtering and plasma CVD.
Continuous deposition of a film on a long strip of substrate is preferable for efficient film formation with high productivity.
A typical device known in the art for conducting such film formation is a roll-to-roll film formation device using a feed roll having a long strip of substrate (a web of substrate) wound into a roll and a take-up roll in which the substrate having a film formed thereon is wound into a roll. This roll-to-roll film formation device continuously forms a film on a long strip of substrate in the film formation chamber while conveying the substrate from the feed roll to the take-up roll along a predetermined pathway passing through the film formation chamber where the film is formed on the substrate by plasma CVD. In this device, the substrate is fed from the feed roll in synchronism with the winding of the substrate having the film formed thereon on the take-up roll.
By the way, a functional film such as a gas barrier film or a protective film is not always a mono-layer film, and a typical functional film known in the art is the one prepared by forming an organic film containing a polymer as its main component on a substrate such as a plastic film, and thereafter forming an inorganic film comprising an inorganic compound on the organic film.
For example, JP 2002-264274 A discloses a gas barrier film prepared by forming an organic film comprising a cured composition containing a monomer or an oligomer of a hexafunctional acrylate or methacrylate, and an inorganic film comprising an oxide selected from aluminum oxide, silicon oxide, a complex oxide of indium and tin, and a complex oxide of indium and cerium.